Distributed ARQ for Wireless Communication System

ABSTRACT

Systems and apparatuss for providing distributed Automatic Repeat Request (ARQ) in a wireless communication system are described herein. In one embodiment, a relay station interconnects a base station of the wireless communication system and one or more mobile stations. A first ARQ process is performed for a first connection between the base station and the relay station. A separate second ARQ process is performed for a second connection between the relay station and a mobile station. In this manner, rather than having end-to-end ARQ between the base station and the mobile station, a distributed ARQ process is provided.

PRIORITY CLAIM

This application is a continuation of and claims the benefit of priorityfrom U.S. patent application Ser. No. 12/922,486, entitled “DistributedARQ for Wireless Communication System” and filed on Oct. 25, 2010, whichis a National Stage of and claims the benefit of priority fromInternational Application No. PCT/IB2009/000515, entitled “DistributedARQ for Wireless Communication System” and filed on Mar. 13, 2009, whichclaims the benefit of priority from U.S. Provisional Patent ApplicationSer. No. 61/036,828, filed on Mar. 14, 2008, all of which are fullyincorporated herein by reference for all purposes.

BACKGROUND

1. Field of the Application

The present invention relates to a wireless communication system andmore particularly relates to distributed Automatic Repeat Request (ARQ)in a wireless communication system.

2. Background of the Disclosure

A relay station is a device that is used to interconnect a base stationand a mobile station in a wireless communication network. By using arelay station, a base station may cover areas that would otherwise beinaccessible to the base station, such as the interior of a shoppingcenter. Automatic Repeat Request (ARQ) is an error control process toachieve reliable data transmission over an unreliable connection. An ARQprocess is desired for a wireless communication network having both basestations and relay stations.

SUMMARY

Systems and methods for providing distributed Automatic Repeat Request(ARQ) in a wireless communication system are described herein. In oneembodiment, a relay station interconnects a base station of the wirelesscommunication system and one or more mobile stations. A first ARQprocess is performed for a first connection between the base station andthe relay station. A separate second ARQ process is performed for asecond connection between the relay station and a mobile station. Inthis manner, rather than having end-to-end ARQ between the base stationand the mobile station, a distributed ARQ process is provided.

In addition, systems and methods for maintaining ARQ continuity during ahandover from the relay station to a target station are disclosedherein. In general, when a mobile station initiates a handover from therelay station providing distributed ARQ to a target station, the relaystation forwards ARQ context information to the target station for anARQ enabled connection between the relay station and the mobile station.More specifically, in one embodiment, if the target station is the basestation serving the relay station, the relay station forwards the ARQcontext information to the base station. Then, by using the ARQ contextinformation, the base station is enabled to continue the ARQ process forthe ARQ enabled connection to the mobile station.

In another embodiment, if the target station is second relay stationserved by the base station, the relay station forwards the ARQ contextinformation to the base station. Then, if the second relay station isoperating in a distributed ARQ mode or otherwise enabled to providedistributed ARQ, the base station forwards the ARQ context informationto the second relay station. By using the ARQ context information, thesecond relay station is then enabled to continue the ARQ process for theARQ enabled connection with the mobile station. If the second relaystation is not operating in a distributed ARQ mode or otherwise enabledto provide distributed ARQ, the base station is enabled to continue theARQ process for the ARQ enabled connection with the mobile station viathe second relay station in an end-to-end, rather than distributed,manner.

In another embodiment, if the target station is a second base station,the relay station forwards the ARQ context information to the basestation. The base station then forwards the ARQ context information tothe second base station via a backhaul network. Then, by using the ARQcontext information, the second base station is enabled to continue theARQ process for the ARQ enabled connection with the mobile station.

In another embodiment, if the target station is a relay station of asecond base station, the relay station forwards the ARQ contextinformation to the base station, which in turn forwards the ARQ contextinformation to the second base station. Then, if the second relaystation is operating in a distributed ARQ mode or otherwise enabled toprovide distributed ARQ, the second base station forwards the ARQcontext information to the second relay station. By using the ARQcontext information, the second relay station is then enabled tocontinue the ARQ process for the ARQ enabled connection with the mobilestation. If the second relay station is not operating in a distributedARQ mode or otherwise enabled to provide distributed ARQ, the secondbase station is enabled to continue the ARQ process for the ARQ enabledconnection with the mobile station via the second relay station in anend-to-end, rather than distributed, manner.

Those skilled in the art will appreciate the scope of the presentinvention and realize additional aspects thereof after reading thefollowing detailed description in association with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thisspecification illustrate several aspects of the invention, and togetherwith the description serve to explain the principles of the invention.

FIG. 1 is a block diagram of a wireless communication network includinga base station, a relay station, and a number of mobile stationsaccording to one embodiment of this disclosure;

FIG. 2 illustrates an end-to-end mode of operation of a relay stationaccording to one embodiment of this disclosure;

FIG. 3 illustrates a distributed mode of operation of a relay stationaccording to one embodiment of this disclosure;

FIG. 4 illustrates exemplary protocol stacks of a base station, a relaystation, and a mobile station when the relay station is operating in adistributed mode according to one embodiment of this disclosure;

FIGS. 5A and 5B illustrate forwarding of Automatic Repeat Request (ARQ)context information from a relay station operating in a distributed modewhen a handover of the mobile station from the relay station to a basestation associated with the relay station occurs according to oneembodiment of this disclosure;

FIGS. 6A through 6C illustrate forwarding of ARQ context informationfrom a relay station operating in a distributed mode when a handover ofthe mobile station from a relay station to another relay stationassociated with the same base station occurs according to one embodimentof this disclosure;

FIGS. 7A and 7B illustrate forwarding of ARQ context information from arelay station operating in a distributed mode when a handover of themobile station from the relay station to a different base station occursaccording to one embodiment of this disclosure;

FIGS. 8A through 8C illustrate forwarding of ARQ context informationfrom a relay station operating in a distributed mode when a handover ofthe mobile station from a relay station to another relay stationassociated with a different base station occurs according to oneembodiment of this disclosure;

FIG. 9 is a block diagram of an exemplary embodiment of the base stationof FIG. 1;

FIG. 10 is a block diagram of an exemplary embodiment of the relaystation of FIG. 1; and

FIG. 11 is a block diagram of an exemplary embodiment of one of themobile stations of FIG. 1.

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information toenable those skilled in the art to practice the invention and illustratethe best mode of practicing the invention. Upon reading the followingdescription in light of the accompanying drawings, those skilled in theart will understand the concepts of the invention and will recognizeapplications of these concepts not particularly addressed herein. Itshould be understood that these concepts and applications fall withinthe scope of the disclosure and the accompanying claims.

FIG. 1 illustrates an exemplary topology of a wireless communicationnetwork 10. In the preferred embodiment, the wireless communicationnetwork 10 operates according to the IEEE 802.16j standard or theadvanced Long Term Evolution (LTE) standard. However, the embodimentsdiscussed herein may be utilized in any type of wireless communicationsystem and are not limited to the IEEE 802.16j or advanced LTE standard.As illustrated, the wireless communication network 10 includes a basestation (BS) 12, a number of relay stations (RSs) 14-1 and 14-2, and anumber of mobile stations (MSs) 16-1 through 16-5. The base station 12is generally implemented at a fixed location. The base station 12operates as a wireless access point for mobile stations, such as themobile station 16-1, located within a wireless coverage area 18 of thebase station 12 as well as for mobile stations, such as the mobilestations 16-2 through 16-5 located within wireless coverage areas 20 and22 of the relay stations 14-1 and 14-2.

The relay stations 14-1 and 14-2 may each be either a fixed relaystation (i.e., a relay station having a fixed location) or a mobilerelay station (i.e., a relay station having a changing location). Forinstance, the relay station 14-1 may be a fixed relay stationimplemented at a shopping center in order to provide wireless access tomobile stations, such as the mobile stations 16-2 and 16-3, locatedwithin the shopping center, and the relay station 14-2 may be a mobilerelay station implemented on a bus in order to provide wireless accessto mobile stations, such as the mobile stations 16-4 and 16-5, locatedwithin the bus. In the preferred embodiment, each of the relay stations14-1 and 14-2 may operate in either an end-to-end mode, which may alsobe referred to herein as a relay station mode, or a distributed mode,which may also be referred to herein as a base station mode. Theoperation modes of the relay stations 14-1 and 14-2 may be configuredduring a network entry. In an alternative embodiment, the relay stations14-1 and 14-2 may have a single mode of operation, which may be eitheran end-to-end mode or a distributed mode, where at least one of therelay stations 14-1 and 14-2 is a distributed mode relay station. Notethat the details of the end-to-end and distributed modes are discussedbelow in detail.

The mobile stations 16-1 through 16-5 may each be a user device having awireless interface for connecting to the wireless communication network10. For example, each of the mobile stations 16-1 through 16-5 may be amobile telephone, a mobile smart phone, a wireless access card for apersonal computer, or the like.

FIG. 2 illustrates the operation of the relay station 14-1 whenoperating in the end-to-end mode according to one embodiment of thisdisclosure. This discussion is equally applicable to the relay station14-2. Also, while the discussion of FIG. 2 focuses on an exemplaryembodiment where the wireless communication network 10 is an IEEE802.16j network, one of ordinary skill in the art will readilyappreciate that the relay station 14-1 operating in end-to-end mode maybe utilized in other types of wireless communication networks uponreading this disclosure. In this embodiment, Internet protocol (IP) flowforwarded by a gateway 24 is received at the base station 12. The basestation 12 maps the IP flow to a MS connection (i.e., a connection toone of the mobile stations 16-1 through 16-5). Using IEEE 802.16j as anexample, the base station 12 creates an IEEE 802.16e medium accesscontrol (MAC) packet data unit (PDU) and may encrypt the MAC PDU. Thebase station 12 forwards the IEEE 802.16e MAC PDU as part of a relay MAC(R-MAC) PDU flow directed toward the relay station 14-1. The R-MAC PDUflow may include one or more IEEE 802.16e MAC PDUs. The relay station14-1 receives the R-MAC PDU flow and directs packets destined toward themobile station 16-2 to the mobile station 16-2 and directs packetsdestined toward the mobile station 16-3 to the mobile station 16-3 asIEEE 802.1e MAC PDU flow. If the MAC PDU flow is encrypted, the mobilestations 16-2 and 16-3 decrypt the IEEE 802.16e MAC PDU. Accordingly,end-to-end connectivity is maintained between the base station 12 andthe mobile stations 16-2 and 16-3 connected via the relay station 14-1.Additionally, end-to-end security and Automatic Repeat Request (ARQ) aremaintained between the base station 12 and the mobile stations 16-2 and16-3 connected via the relay station 14-1.

FIG. 3 illustrates the operation of the relay station 14-1 whenoperating in the distributed mode according to one embodiment of thisdisclosure. This discussion is equally applicable to the relay station14-2. Also, while the discussion of FIG. 3 focuses on an exemplaryembodiment where the wireless communication network 10 is an IEEE802.16j network, one of ordinary skill in the art will readilyappreciate that the relay station 14-1 operating in distributed mode maybe utilized in other types of wireless communication networks uponreading this disclosure. In this embodiment, a transport connection isestablished between the base station 12 and the relay station 14-1 thatis dedicated for relaying mobile station traffic, which is traffic toand/or from the mobile stations 16-2 and 16-3 served by the relaystation 14-1. Connections are also established between the relay station14-1 and the mobile stations 16-2 and 16-3. Using a downlink as anexample, the base station 12 maps downlink service data flows to themobile stations 16-2 and 16-3 served by the relay station 14-1 to thetransport connection of the relay station 14-1. The relay station 14-1maps the downlink service data flows from the base station 12 to therespective connections of the mobile stations 16-2 and 16-3. In asimilar manner, uplink service data flows from the mobile stations 16-2and 16-3 are provided to the relay station 14-1 via the correspondingconnections, and the relay station 14-1 maps the uplink service dataflows from the mobile stations 16-2 and 16-3 to the transport connectionto the base station 12. As such, security, connectivity, and ARQ may bemaintained between the base station 12 and the relay station 14-1, andseparately maintained between the relay station 14-1 and the mobilestations 16-2 and 16-3.

Specifically, with respect to ARQ, an ARQ process is performed by thebase station 12 and the relay station 14-1 for the transport connectiondedicated for relaying mobile station traffic. In addition, if one ormore ARQ enabled connections are made between the relay station 14-1 andthe mobile station 16-2, a separate ARQ process is performed by therelay station 14-1 and the mobile station 16-2 for each of the ARQenabled connections. Likewise, if one or more ARQ enabled connectionsare made between the relay station 14-1 and the mobile station 16-3, aseparate ARQ process is performed by the relay station 14-1 and themobile station 16-3 for each of the ARQ enabled connections. In thismanner, rather than having an end-to-end ARQ process between the basestation 12 and each of the mobile stations 16-2 and 16-3, ARQ isdistributed in that an ARQ process is performed for the transportconnection between the base station 12 and the relay station 14-1 andseparate ARQ processes are performed between the relay station 14-1 andthe mobile stations 16-2 and 16-3.

Distributed ARQ is beneficial because it reduces overhead in thewireless communication network 10. More specifically, ARQ related dataflow does not need to be relayed between the base station 12 and themobile stations 16-1 through 16-5 for each ARQ enabled connection of themobile stations 16-1 through 16-5. In addition, there is reduced delayfor distributed ARQ as compared to end-to-end ARQ. In addition,distributed ARQ is particularly beneficial for mobile relay stations.

FIG. 4 graphically illustrates an exemplary protocol stack for the basestation 12, the relay station 14-1, and the mobile station 16-2. Inaddition, FIG. 4 illustrates an exemplary protocol stack of a standardrelay primarily to be contrasted with the protocol stack of the relaystation 14-1. As illustrated in FIG. 4, the base station 12 maintains aconvergence layer and a MAC layer with the relay station 14-1, while therelay station 14-1 maintains a separate convergence layer and a separateMAC layer with the mobile station 16-2. The relay station 14-1 alsomaintains a physical (PHY) layer with the mobile station 16-2. In thisexample, the base station 12 also maintains a PHY layer and a MAC layer,which for IEEE 802.16 are an R-PHY layer and an R-MAC layer, with thestandard relay. The standard relay also maintains a MAC layer and a PHYlayer, which for IEEE 802.16 are an R-PHY layer and an R-MAC layer, withthe relay station 14-1. Note that, as discussed above and illustrated inFIG. 4, the ARQ maintained between the base station 12 and the relaystation 14-1 is separate from the ARQ maintained between the relaystation 14-1 and the mobile station 16-2.

When operating to provide distributed ARQ, the relay stations 14-1 and14-2 store ARQ context information for each of the ARQ enabledconnections with the mobile stations 16-2 through 16-5. For a particularconnection, the ARQ context information for that connection includesinformation defining the state of the ARQ process. As an example, forIEEE 802.16, the ARQ context information for a particular connection mayinclude ARQ related variables such as ARQ TX WINDOW START, ARQ RXHIGHEST BST, and the like. Note, however, that the ARQ contextinformation may vary depending on the particular implementation.

Using the mobile station 16-2 as an example, when the mobile station16-2 performs a handover from the relay station 14-1 to a targetstation, the relay station 14-1, which is operating in the distributedARQ mode, forwards the ARQ context information for each ARQ enabledconnection of the mobile station 16-2 to the base station 12. The targetstation may be the base station 12, another relay station served by thebase station 12 such as the relay station 14-2, another base station, oranother relay station of another base station. Based on the forwardedARQ context information, the target station is enabled to maintain theARQ process for each of the ARQ enabled connections of the mobilestation 16-2. As a result, continuity of the ARQ process for each of theARQ enabled connections of the mobile station 16-2 is maintained throughand following handover.

FIGS. 5A and 5B illustrate the forwarding of the ARQ context informationfor the mobile station 16-2 during handover of the mobile station 16-2from the relay station 14-1 to the base station 12 according to oneembodiment of this disclosure. As illustrated in FIG. 5A, in thisembodiment, the mobile station 16-2 moves from the wireless coveragearea 20 of the relay station 14-1 into the wireless coverage area 18 ofthe base station 12. In response, a handover process is performed, aswill be appreciated by one of ordinary skill in the art upon readingthis disclosure. As illustrated in FIG. 5B, once the handover process isinitiated (step 100), the relay station 14-1 forwards the ARQ contextinformation for one or more ARQ enabled connections to the mobilestation 16-2 to the base station 12 (step 102). Based on the ARQ contextinformation, the base station 12 is then enabled to continue the ARQprocess for each of the ARQ enabled connections to the mobile station16-2 (step 104). As a result, continuity for the ARQ process ismaintained during and after the handover process. Note that FIG. 5B onlyillustrates the forwarding of the ARQ context information for clarity.However, as will be appreciated by one of ordinary skill in the art uponreading this disclosure, numerous additional steps not illustrated inFIG. 5B are typically performed during the handover process.

FIGS. 6A through 6C illustrate the forwarding of the ARQ contextinformation for the mobile station 16-2 during handover of the mobilestation 16-2 from the relay station 14-1 to the relay station 14-2 ofthe base station 12 according to one embodiment of this disclosure. Asillustrated in FIG. 6A, in this embodiment, the mobile station 16-2moves from the wireless coverage area 20 of the relay station 14-1 intothe wireless coverage area 22 of the relay station 14-2. In response, ahandover process is performed, as will be appreciated by one of ordinaryskill in the art upon reading this disclosure. As illustrated in FIG.6B, once the handover process is initiated (step 200), the relay station14-1 forwards the ARQ context information for one or more ARQ enabledconnections of the mobile station 16-2 to the base station 12 (step202). In this embodiment, the relay station 14-2 operates in theend-to-end mode. As such, based on the ARQ context information, the basestation 12 is then enabled to continue the ARQ process for each of theARQ enabled connections to the mobile station 16-2 via the relay station14-2 in an end-to-end manner (steps 204A/204B). As a result, continuityfor the ARQ process is maintained during and after the handover process.

FIG. 6C illustrates the ARQ forwarding process if the relay station 14-2operates in the distributed mode. As illustrated, once the handoverprocess is initiated (step 300), the relay station 14-1 forwards the ARQcontext information for one or more ARQ enabled connections of themobile station 16-2 to the base station 12 (step 302). In thisembodiment, the relay station 14-2 operates in the distributed mode. Assuch, the base station 12 forwards the ARQ context information to therelay station 14-2 (step 304). Then, based on the ARQ contextinformation, the relay station 14-2 is then enabled to continue the ARQprocess for each of the ARQ enabled connections to the mobile station16-2 (step 306). As a result, continuity for the ARQ process ismaintained during and after the handover process. Again, note that FIGS.6B and 6C only illustrate the forwarding of the ARQ context informationfor clarity. However, as will be appreciated by one of ordinary skill inthe art upon reading this disclosure, numerous additional steps notillustrated in FIGS. 6B and 6C are typically performed during thehandover process.

FIGS. 7A and 7B illustrate the forwarding of the ARQ context informationfor the mobile station 16-2 during handover of the mobile station 16-2from the relay station 14-1 to a base station 26 other than the basestation 12 according to one embodiment of this disclosure. Asillustrated in FIG. 7A, in this embodiment, the mobile station 16-2moves from the wireless coverage area 20 of the relay station 14-1 intoa wireless coverage area 28 of the base station 26. In response, ahandover process is performed, as will be appreciated by one of ordinaryskill in the art upon reading this disclosure. As illustrated in FIG.7B, once the handover process is initiated (step 400), the relay station14-1 forwards the ARQ context information for one or more ARQ enabledconnections of the mobile station 16-2 to the base station 12 (step402). The base station 12 then forwards the ARQ context information tothe base station 26 preferably via a backhaul network (step 404). Basedon the ARQ context information, the base station 26 is then enabled tocontinue the ARQ process for each of the ARQ enabled connections to themobile station 16-2 (step 406). As a result, continuity for the ARQprocess is maintained during and after the handover process. Note thatFIG. 7B only illustrates the forwarding of the ARQ context informationfor clarity. However, as will be appreciated by one of ordinary skill inthe art upon reading this disclosure, numerous additional steps notillustrated in FIG. 7B are typically performed during the handoverprocess.

FIGS. 8A through 8C illustrate the forwarding of the ARQ contextinformation for the mobile station 16-2 during handover of the mobilestation 16-2 from the relay station 14-1 to a relay station 30 of thebase station 26 according to one embodiment of this disclosure. Asillustrated in FIG. 8A, in this embodiment, the mobile station 16-2moves from the wireless coverage area 20 of the relay station 14-1 intoa wireless coverage area 32 of the relay station 30. In response, ahandover process is performed, as will be appreciated by one of ordinaryskill in the art upon reading this disclosure. As illustrated in FIG.8B, once the handover process is initiated (step 500), the relay station14-1 forwards the ARQ context information for one or more ARQ enabledconnections of the mobile station 16-2 to the base station 12 (step502). The base station 12 then forwards the ARQ context information forthe one or more ARQ enabled connections of the mobile station 16-2 tothe base station 26 preferably via a backhaul network (step 504). Inthis embodiment, the relay station 30 operates in the end-to-end mode.As such, based on the ARQ context information, the base station 12 isthen enabled to continue the ARQ process for each of the ARQ enabledconnections to the mobile station 16-2 via the relay station 30 in anend-to-end manner (steps 506A/506B). As a result, continuity for the ARQprocess is maintained during and after the handover process.

FIG. 8C illustrates the ARQ forwarding process if the relay station 30operates in the distributed mode. As illustrated, once the handoverprocess is initiated (step 600), the relay station 14-1 forwards the ARQcontext information for one or more ARQ enabled connections of themobile station 16-2 to the base station 12 (step 602). The base station12 then forwards the ARQ context information for the one or more ARQenabled connections of the mobile station 16-2 to the base station 26preferably via a backhaul network (step 604). In this embodiment, therelay station 30 operates in the distributed mode. As such, the basestation 12 forwards the ARQ context information to the relay station 30(step 606). Then, based on the ARQ context information, the relaystation 30 is enabled to continue the ARQ process for each of the ARQenabled connections of the mobile station 16-2 (step 608). As a result,continuity for the ARQ process is maintained during and after thehandover process. Again, note that FIGS. 8B and 8C only illustrate theforwarding of the ARQ context information for clarity. However, as willbe appreciated by one of ordinary skill in the art upon reading thisdisclosure, numerous additional steps not illustrated in FIGS. 8B and 8Care typically performed during the handover process.

FIG. 9 is a block diagram of an exemplary embodiment of the base station12 of FIG. 1. As illustrated, the base station 12 includes a controlsystem 34, which may have associated memory 36. The control system 34 isimplemented in hardware. For instance, the control system 34 may be oneor more Central Processing Units (CPUs), one or more ApplicationSpecific Integrated Circuits (ASICs), one or more Field ProgrammableGate Arrays (FPGAs), or the like. The functionality of the base station12 discussed herein may be implemented in software executed by thecontrol system 34, implemented in hardware within the control system 34,or a combination thereof. The base station 12 also includes one or morewireless network interfaces 38 for communicating with the relay stations14-1 and 14-2 (FIG. 1) and mobile stations, such as the mobile station16-1, located within the wireless coverage area 18 of the base station12. Lastly, the base station 12 includes a backhaul network interface 40for communicating with other base stations via a backhaul network. Thebackhaul network may be a high speed wired or wireless network.

FIG. 10 is a block diagram of an exemplary embodiment of the relaystation 14-1 of FIG. 1. This discussion is equally applicable to therelay station 14-2. As illustrated, the relay station 14-1 includes acontrol system 42, which may have associated memory 44. The controlsystem 42 is implemented in hardware. For instance, the control system42 may be one or more CPUs, one or more ASICs, one or more FPGAs, or thelike. The functionality of the relay station 14-1 discussed herein maybe implemented in software executed by the control system 42,implemented in hardware within the control system 42, or a combinationthereof. The relay station 14-1 also includes one or more wirelessnetwork interfaces 46 for communicating with the base station 12 andmobile stations, such as the mobile stations 16-2 and 16-3, locatedwithin the wireless coverage area 20 of the relay station 14-1.

FIG. 11 is a block diagram of an exemplary embodiment of the mobilestation 16-1. This discussion is equally applicable to the other mobilestations 16-2 through 16-5. As illustrated, the mobile station 16-1includes a control system 48, which may have associated memory 50. Thecontrol system 48 is implemented in hardware. For instance, the controlsystem 48 may be one or more CPUs, one or more ASICs, one or more FPGAs,or the like. The functionality of the mobile station 16-1 discussedherein may be implemented in software executed by the control system 48,implemented in hardware within the control system 48, or a combinationthereof. The mobile station 16-1 also includes a wireless networkinterface 52 for communicating with the base station 12. Note that ifthe mobile station 16-1 were to move to the wireless coverage area 20 ofthe relay station 14-1, then the wireless network interface 52 wouldthen enable the mobile station 16-1 to communicate with the relaystation 14-1. The mobile station 16-1 also includes a user interface 54,which may include components such as a speaker, a microphone, a display,a keypad, or the like.

Those skilled in the art will recognize improvements and modificationsto the embodiments of the present invention. All such improvements andmodifications are considered within the scope of the concepts disclosedherein and the claims that follow.

What is claimed is:
 1. A computer-program storage apparatus foroperating a relay station associated with a base station in a wirelesscommunication network comprising at least one memory having one or moresoftware modules stored thereon, the one or more software modules beingexecutable by one or more control systems and the one or more softwaremodules comprising: code for maintaining, by the relay station, a firstconnection to the base station, wherein a first Automatic Repeat Request(ARQ) process is performed for the first connection between the relaystation and the base station; code for maintaining, by the relaystation, a second connection to a mobile station within a wirelesscoverage area of the relay station; and code for maintaining, by therelay station, a second ARQ process for the second connection betweenthe relay station and the mobile station.
 2. The apparatus of claim 1,wherein the relay station is a mobile relay station.
 3. The apparatus ofclaim 1, wherein the relay station is a fixed relay station.
 4. Theapparatus of claim 1, wherein the relay station serves a plurality ofmobile stations, including the mobile station, within the wirelesscoverage area of the relay station and the first connection is atransport connection for downlink data for the plurality of mobilestations, and the apparatus comprises: code for maintaining, by therelay station, a plurality of second connections, including the secondconnection, to the plurality of mobile stations, each of the pluralityof second connections being for one of the plurality of mobile stationsand at least some of the plurality of second connections being ARQenabled.
 5. The apparatus of claim 4, comprising code for maintaining,by the relay station, a separate ARQ process for each of the pluralityof second connections that is ARQ enabled.
 6. The apparatus of claim 1,further comprising, when a handover occurs for the mobile station fromthe relay station to the base station, code for communicating, by therelay station, ARQ context information to the base station for thesecond ARQ process such that the base station is enabled to continue thesecond ARQ process with the mobile station.
 7. The apparatus of claim 1,further comprising, when a handover occurs for the mobile station fromthe relay station to a second relay station that is associated with thebase station and operates in an end-to-end ARQ mode, code forcommunicating, by the relay station, ARQ context information to the basestation for the second ARQ process such that the base station is enabledto continue the second ARQ process with the mobile station via thesecond relay station in an end-to-end manner.
 8. The apparatus of claim1, further comprising, when a handover occurs for the mobile stationfrom the relay station to a second relay station that is associated withthe base station and operates in a distributed ARQ mode, code forcommunicating, by the relay station, ARQ context information to the basestation for the second ARQ process such that the base station forwardsthe ARQ context information for the second ARQ process to the secondrelay station and the second relay station is enabled to continue thesecond ARQ process with the mobile station.
 9. The apparatus of claim 1,further comprising, when a handover occurs for the mobile station fromthe relay station to a second base station, code for communicating, bythe relay station, ARQ context information to the base station for thesecond ARQ process such that the base station forwards the ARQ contextinformation for the second ARQ process to the second base station andthe second base station is enabled to continue the second ARQ processwith the mobile station.
 10. The apparatus of claim 1, furthercomprising, when a handover occurs for the mobile station from the relaystation to a second relay station that is associated with a second basestation and operates in an end-to-end ARQ mode, code for communicating,by the relay station, ARQ context information to the base station forthe second ARQ process such that the ARQ context information for thesecond ARQ process is forwarded to the second base station via the basestation and the second base station is enabled to continue the secondARQ process with the mobile station via the second relay station in anend-to-end manner.
 11. The apparatus of claim 1, further comprising,when a handover occurs for the mobile station from the relay station toa second relay station that is associated with the base station andoperates in a distributed ARQ mode, code for communicating, by the relaystation, ARQ context information to the base station for the second ARQprocess such that the ARQ context information for the second ARQ processis forwarded to the second relay station via the base station and thesecond base station and the second relay station is enabled to continuethe second ARQ process with the mobile station.
 12. An apparatus foroperating a relay station associated with a base station in a wirelesscommunication network comprising: means for maintaining, by the relaystation, a first connection to the base station, wherein a firstAutomatic Repeat Request (ARQ) process is performed for the firstconnection between the relay station and the base station; means formaintaining, by the relay station, a second connection to a mobilestation within a wireless coverage area of the relay station; and meansfor maintaining, by the relay station, a second ARQ process for thesecond connection between the relay station and the mobile station.